Module 5 / Unit 3 Installing Wireless Networks Flashcards
On completion of this unit, you will be able to: □ Distinguish between different IEEE 802.11 Wi-Fi standards and topologies. □ Perform a site survey and understand issues impacting on site design. □ Troubleshoot wireless connectivity, configuration, and security issues.
What mechanism does RTS/CTS support?
Collision avoidance (CSMA/CA). Rather than try to detect collisions, a wireless station indicates its intent to transmit by broadcasting a Request To Send (RTS) and waits to receive a Clear To Send (CTS) before proceeding.
Which IEEE WLAN standards specify a data transfer rate of up to 54 Mbps?
802.11a and 802.11g.
What options may be available for an 802.11n network that are not supported under 802.11g?
Channel bonding, Multiple-Input-Multiple-Output (MIMO), and use of either 2.4 GHz or 5 GHz frequency bands.
True or false? Stations with 802.11ac capable adapters should be assigned to the 5 GHz frequency band.
True - 802.11ac is designed to work only in the 5 GHz frequency band with the 2.4 GHz band used for legacy clients.
What is a BSSID?
The MAC address of an access point (or a random address in the case of ad hoc WLANs).
What are the advantages of deploying a wireless mesh topology over an ad hoc one?
Stations in a Wireless Mesh Network are capable of discovering one another, forming peering arrangements, and performing path discovery and forwarding between peers (routing).
True or false? Suppressing transmission of the WLAN beacon improves security.
False - the beacon cannot be suppressed completely. Increasing the broadcast interval reduces network overhead but increases the time required to find and connect to the network.
What constraints should you consider when planning the placement of an access point?
Range, interference and obstructions, number of clients (device density and bandwidth requirements), and access to a network port and power supply.
What is beamforming?
Beamforming or Multiuser MIMO (MU-MIMO) is a means of performing primitive switching with an access point. The AP can send a signal more strongly to clients positioned along different axes.
Which frequency band is less likely to suffer from co-channel interference?
The 5 GHz band.
What is a heat map?
A site survey plotting the strength of wireless signals in different parts of a building.
Widget Corporation has provided wireless access for its employees using several access points located in different parts of the building. Employees connect to the network using 802.11g-compatible network cards. On Thursday afternoon, several users report that they cannot log on to the network. What troubleshooting step would you take first?
Check whether the problem machines are trying to utilize the same access point.
Your office block is hosting a conference event. During the morning coffee break, several guests report that they cannot access their webmail. What is the likely cause?
Device saturation - the access point is likely to be experiencing greater load than usual and cannot cope with the volume of requests.
What is the main difference between WPA and WPA2?
WPA2 supports a stronger encryption algorithm, based on AES.
Why might an attacker launch a jamming attack against a wireless access point?
This could be a simple Denial of Service (DoS) attack but the attacker could also be attempting to use an evil twin / rogue AP to intercept network traffic.
